1. Field of the Invention
The present invention relates to a feedthrough ceramic capacitor and a support for fixing the feedthrough ceramic capacitor.
2. Description of the Related Art
Feedthrough ceramic capacitors are generally used in LC composite part devices used as filters.
High-voltage LC composite part devices uses feedthrough ceramic capacitors as line filters for oscillators using magnetrons used in high-frequency large-power apparatuses such as microwave ovens, or the like. Such high-voltage LC composite part devices are taken notice as a social problem because noise pollution is caused by electromagnetic wave leaked out of those devices. To prevent such noise pollution, various kinds of line filters have been heretofore proposed.
FIG. 4A shows the configuration of a conventional feedthrough ceramic capacitor used as the aforementioned line filter.
In the conventional feedthrough ceramic capacitor 59, two through-holes are formed at a certain interval therebetween in a piece of dielectric porcelain 52 constituting a capacitor. The dielectric porcelain 52 has individual electrodes 51b provided on its one surface independently of each other, and a common electrode 51a provided on its other surface. Feedthrough conductors 53a and 53b pass through the through-holes. The independent electrodes 51b are connected to the feedthrough conductors 53a and 53b, respectively, through connection fittings 61, or the like, by soldering, or the like. Further, the feedthrough conductors 53a and 53b are covered with electrically insulating tubes 54 so as to be kept electrically insulated from the common electrode 51a. These main portions constituting a feedthrough ceramic capacitor are put in housing parts 57 and 58 and fixed by resins 55 and 56.
Here, the common electrode 51a is connected to a grounding fitting 60 and the grounding fitting 60 is led to the outside directly so as to be exposed to the outside of the housing.
When the conventional feedthrough ceramic capacitor 59 having the aforementioned configuration is to be used as a high-voltage LC composite part device for preventing noise of a magnetron, or the like, as shown in FIG. 4B, the feedthrough ceramic capacitor 59 is inserted into an insertion hole 62 of a metal support 63 such as a filter box fixed to the magnetron so that the grounding fitting 60 of the feedthrough ceramic capacitor 59 and the metal support 63 are fixed to each other by screws 58, eyelet caulking, or the like, by using through-holes 64a formed in the four corners of the grounding fitting 60 and through-holes 64b formed in the support 63.
Then, the feedthrough ceramic capacitor 59 and an inductor are connected to each other in the inside of the metal support 63. Thus, the LC composite part device which is a line filter used for preventing noise of the magnetron, or the like, is formed.
A feedthrough ceramic capacitor is generally mounted to a filter box which is a metal support having the ground potential (hereinafter referred to as "filter box"). Here, the feedthrough ceramic capacitor used in a high-frequency large-power apparatus using a magnetron which is apt to cause a problem of high-frequency noise is fixed to the filter box by screws, eyelet caulking, or the like.
Such a fixing work, however, must be performed by hand thoroughly, so that the workability is poor.
Further, in the fixture method in which the feedthrough ceramic capacitor is fixed to the support by using four holes formed in the grounding fitting of the feedthrough ceramic capacitor, adhesion is poor so that high-frequency noise generated by the high-frequency apparatus may leak to the outside through a gap in the contact surface between the grounding fitting and a side plate of the filter box.